The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
It is often desirable to determine the torque on a rotating shaft (rotator) relative to a stationary component (stator). A typical application that includes a rotator and a stator is an automatic transmission.
In order to determine the torque being applied to the rotator, a torque sensor is used to measure the torque. Common torque sensors include strain gages, magnetic or optical sensors, and surface acoustic wave (SAW) sensors. These torque sensors each measure various parameters such as local strain, angular displacement, or strained-induced change on an acoustic wave. Typically these torque sensors have two components including what can generally be referred to as a transmitter and a receiver. The receiver is typically coupled to the rotator and the transmitter is coupled to the stator. In the case of magnetic sensors and SAW sensors, a current is induced through the transmitter and torque applied on the rotator is transmitted back to the transmitter in a form of current, radio signal or magnetic field which is then converted into an estimated torque. One crucial element to determining the amount of torque using these sensors is knowing and controlling the gap distance between the transmitter and receiver.
Accordingly, one limitation of the above described torque sensors is that any discrepancy in the expected gap distance used in calculating the torque from the actual gap distance between the receiver and the transmitter can increase the margin of error in the torque calculation. Because the system tolerances between the rotator and the stator are often not precisely known, at best the expected gap distance will be an estimate. Therefore, there is room in the art to provide a device that reduces the error between the expected gap distance and the actual gap distance.